1. Field of the Invention
The present invention provides a switching circuit, and more particularly, a power switching circuit.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram illustrating a conventional power switching circuit 100. As shown in FIG. 1, the power source 110 is coupled to a controller 120 and a switch 130. The switch 130 comprises a first end coupled to the power source 110, a second end coupled to an output end for outputting the power received on the first end of the switch 130, and a control end coupled to the controller 120. The power source 110 provides power to the controller 120 so as to enable the controller 120 to work and to control the behavior of the switch 130. The controller 120 controls the switch 130 to output power or not.
Please refer to FIG. 2. FIG. 2 is a diagram illustrating the switch 130. The switch 130 is realized with a P type Metal Oxide Semiconductor (PMOS) transistor. The controller 120 controls the PMOS transistor to be turned on or turned off for outputting the power source 110.
The drawback of the conventional power switching circuit 100 is the controller 120 has to be always activated no matter whether the switch 130 outputs the power source 110 or not. That is, the controller 120 keeps consuming power from the power source 110 and that causes power wasting.